'They love it' or 'They are loving it'?
When a verb describes a state and not an action we do not use the continuous tense. For example, 'play' is an action so we can say 'playing' whereas 'be' is a fixed state which does not change: 'To be, or not to be'.
Grammatically it is not correct to say "Im loving it" even though McDonald's have made this expression famous. 'Love' is a state verb and so we should say "I love it".
State verbs generally fall into 4 groups:
Emotion: love, hate, want, need
Possession: have, own, want, belong
Sense: see, hear, smell, seem
Thought: know, believe, remember
Here are some more examples of state verbs:
State Verbs
doubt dislike understand suspect
loathe own belong know
like need want seem
mean believe forget remember
prefer hate love see